Spray-dried agent for finishing textiles

ABSTRACT

A SPRAY-DRIED AGENT FOR TEXTILE FINISHING WHICH CONTAINS AS ACTIVE COMPONENTS AT LEAST ONE METHYLOL COMPOUND OF UREA AND, AS A STABILISER TO INCREASE STABILITY IN STORAGE, A SMALL AMOUNT OF A FIVE- TO SEVEN-MEMBERED HETEROCYCLIC COMPOUND HAVING ONE OF THE GROUPINGS   -NH-CO-NH-,-NH-CO-CH2OR   -NH-CO-O-   IN THE RING OR A METHYLOL DERIVATIVE OF SUCH A HETEROCYCLIC COMPOUND.

United States Patent US. Cl. 260-553 R 8 Claims ABSTRACT OF THE DISCLOSURE A spray-dried agent for textile finishing which contains as active components at least one methylol compound of urea and, as a stabiliser to increase stability in storage, a small amount of a fiveto seven-membered heterocyclic compound having one of the groupings in the ring or a methylol derivative of such a heterocyclic compound.

It is known that methylol compounds of urea may be used as agents for textile finishing, particularly for creaseresist finishing and shrink-resist finishing of textiles which consist of or contain cellulose.

These agents have hitherto usually been manufactured and sold as aqueous pastes prepared from urea and formaldehyde in a molar ratio of from about 1:1.4 to 1122. These pastes have the disadvantage that they have little stability in storage because they gradually condense into higher molecular weight products. Experiments aimed at drying such pastes into solid finishing agents on a commercial scale have hitherto only been successful when the pastes had been prepared from urea and formaldehyde in a molar ratio of 1:19 to 1:2.2. It is furthermore known that dimethylolurea may be prepared in solid form. The said solid substances have the advantage that they have fairly low solubility in water and a low rate of dissolution which makes it diflicult to prepare liquors ready for use. Moreover they, too, have insufficient stability in storage and some of them are converted relatively rapidly like the said pastes into sparingly soluble or insoluble higher molecular Weight products which are troublesome in textile finishing. Monomethylolurea can also be prepared in solid form, but like dimethylolurea it has in adequate stability in storage.

According to an earlier proposal, textile finishing agents which may have been spray-dried and which are solid mixtures containing a maximum of 0.3% by weight of free formaldehyde, contain urea and/or monomethylolurea and dimethylolurea in such amounts that the molar ratio of free and combined urea to combined formaldehyde is from 121.4 to 1:1.85, have much better watersolubility and stability than the abovementioned agents. In order that these agents may be stored satisfactorily even under unfavorable conditions, however, it is sometimes desirable to further improve their stability in the solid condition.

It is the object of the present invention to provide a spray-dried solid textile finishing agent which contains as active component at least one methylol compound of urea and which is distinguished by particularly marked stability in storage in the dry condition and in the form of its aqueous solutions. Other objects will become ap- Patented Mar. 21, 1972 parent upon reading the following description and disclosure.

These objects are achieved in accordance with this invention.

We have found that a spray-dried textile finishing agent containing as active component at least one methylol compound of urea is superior to all the abovementioned agents of this type in storage stability when it contains 2 to 8%, preferably 3 to 6%, by weight (with reference to the methylol compounds of urea) of at least one substance having the general formula:

ZC=O iZ-IC in which Z denotes one of the radicals NH and N(CH OH), X denotes one of the radicals NH, N(CH OH)-, CH and 0- and Y denotes a 1,2-alkylene radical, 1,3-alkylene radical or 1,4-alkylene radical which may bear hydroxyl groups, alkyl groups and/or alkoxyl groups each bearing up to four carbon atoms as substituents, and not more than 2% by weight of water.

Examples of substances having the formula I are:

imidazolidone-Z, 4-methylimidazolidone-2, 4,S-dihydroxyimidazolidone-Z,

4,5 -dimethoxyimidazolidone-2, hexahydropyrimidone-Z, 4-hydroxyhexahydropyrimidone-2, 4-butoxyhexahydropyrimidone-2, 4-methoxy-5 ,5 -dimethylhexahydropyrimidone-2, 5-hydroxyhexahydropyrimidone-Z, oxazolidone,

pyrrolidone-Z,

piperidone-Z,

epsilon-caprolactam and derivatives of the said substances which are wholly or partly substituted by methylol groups, i.e. hydroxymethyl groups, on the nitrogen atoms.

Substances having the Formula I are contained in the agents according to this invention in amounts of 2 to 8%, preferably 3 to 6%, by Weight with reference to the methylol compounds of urea. They may be added at any time during the production of the agents, particularly prior to or during the spray drying. It is preferable to add them to the aqueous mixture which is to be spray-dried, during or after the reaction of urea with formaldehyde.

In other respects, the agent according to this invention may be prepared by conventional methods. Thus for example urea and formaldehyde may be reacted with each other in a molar ratio of 1:1.4 to 1:22 in aqueous solution at a pH value of 6.5 to 9 and at a temperature of up to C. and the reaction product supplied to a spray dryer, the substances having the Formula I being added either during the dissolution of the urea, or after the formaldehyde has been added at any stage of the reaction, or after the reaction is over immediately prior to or during spray drying.

It has proved to be particularly advantageous for the spray drying not to be carried out immediately after the reaction but for the aqueous reaction product to be allowed to crystallize out for a fairly long period at low temperature and to subject to spray drying the crystal mash obtained, to which the substance having the formula I has preferably already been added. The following procedure is therefore particularly preferred:

Urea and formaldehyde are reacted with each other in a molar ratio of 1:1.4 to 1:1.85, preferably 1: 1.55 to 1:1.8, with or without adding the abovementioned amounts of substances having the Formula I, in aqueous solution at a pH value of 6.5 to 8.5, preferably 7.0 to 8.0, and at a temperature of 30 to 40 C. for up to five hours, preferably from half an hour to two hours, the reaction mixture is cooled to 15 to 28 C., stirred for at least 24 hours, preferably for 30 to 70 hours, at the said temperature (the substance having the Formula I being if desired added at this point and not earlier) and the resultant crystal slurry is subjected to spray drying.

To adjust the pH value of the reaction solution, an alkaline-reacting substance is used; medium-strength organic bases are particularly suitable for this purpose because when the'y are used end products are obtained which are particularly stable in storage. Examples of bases are: low molecular weight alkanolamines, particularly those having up to six carbon atoms in the molecule, such as triethanolamine, diethanolamine, N-methylethanolamine and N-dimethylethanolamine.

It is particularly advantageous for the crystal slurry intended for spray drying to have a dry residue of at least 30% by weight. Products having particularly good stability in storage are obtained from crystal pastes having a dry residue of 40 to 50% by weight; these pastes can also be easily conveyed and atomized. The production of the crystal pastes may be carried out batchwise or continuously for example in a cascade of stirred vessels.

Drying the crystal slurry in order to obtain the end product may be carried out in nozzle or disc spray dryers. It has proved to be particularly advantageous for the inlet temperature of the spray dryer to be from 135 to 170 C., preferably from 140 to 160 C., and for the outlet temperature of the spray dryer to be from 50 to 80 0., preferably from 60 to 75 C. It is advantageous to cool the material discharge from the dryer as quickly as possible to a temperature of 40 C. or less, for example by means of a cooling channel.

Care should be taken in the drying that the water content of the finished product does not exceed 2% by weight, because the water content also exerts a considerable influence on the stability in storage of the agent according to the invention. Water contents below this limit are in general obtained without difliculty when the abovementioned drying conditions are maintained.

The agents according to this invention have much better stability in storage than agents which do not contain substances having Formula I but are otherwise identical. Moreover their aqueous solutions, particularly in concen trated form, have a considerably better storage life; stock solutions of the agents according to this invention may therefore be kept for days without detriment.

The invention is further illustrated by the following examples in which the parts and percentages specified are by weight.

EXAMPLE 1 60 parts of urea is mixed with 40 parts of water and such an amount of 35% aqueous formaldehyde solution is added thereto that the molar ratio of urea to formaldehyde is 1:17 A solution having a substance content of 45% is obtained. Half of the mixture has 6% of pyrrolidone-2 added to it with reference to the substance contained in the solution. Both halves are adjusted to a pH value of 7.5 to 7.7 with triethanolamine, condensed for two hours at 35 C. and then allowed to crystallize while being stirred for sevent'y hours at 21 to 25 C. The crystal slurries obtained are spray-dried, the inlet temperature of the dryer being 150 C. and the outlet temperature being 70 C. The powder obtained contains 1.2% of water in the case of the product free from pyrrolidone and 1.4% of water in the case of the product containing pyrrolidone according to the invention.

Both products dissolve in water without any residue immediately after their production. They are then stored for forty days at 40 C. After this period, the agent according to the invention contains 0.16% of constituents which are insoluble in water while the agent free from pyrrolidone contains 1% of constituents which are insoluble in water.

EXAMPLE 2 60 parts of urea, 40 parts of water and such an amount of 35% aqueous formaldehyde solution are mixed that the molar ratio of urea to formaldehyde is 1:1.75; the mixture is adjusted to a pH value of 7.8 with triethanolamine, condensed for one hour at 35 C. and then allowed to crystallize for sixty-nine hours at 20 to 24 C. while stirring. 2% of pyrrolidone (with reference to the solids contained therein) is added to half of the mixture. One hour later the two halves are spray-dried as described in Example 1. The samples, which give clear solutions in water and which contain 0.92% of water (product free from pyrrolidone) and 0.84% of water (product according to this invention) are stored for fifty days at 40 C. After this period the agent according to this invention contains 0.4% of constituents which are insoluble in water while the agent free from pyrrolidone contains 1.33% of water-insoluble constituents.

EXAMPLE 3 The procedure of Example 2 is followed but omitting pyrrolidone-2 (sample 1). Further samples are prepared in the same way. Samples 2 and 3 have 3% and 5% of imidazolidone-2 added to them prior to condensation and Samples 4 and 5 have 3% and 5% of imidazolidone-2 added to them one hour prior to spray drying. All the samples are free from water-insoluble constituents immediately after the spray drying. They contain the following amounts of water:

Percent Sample: water 1 0.5 1

The samples are kept at 40 C. for seven weeks. After this period they contain the following amounts of waterinsoluble constituents.

Percent insoluble 1 0.79 2 0.32

Sample:

The agents according to this invention, Samples 2 to 5, are therefore more stable in storage than the agent free from additive although they contain more water.

The same good results are achieved, if in Samples 2 to 5 the imidazolidone-Z is replaced by the same quantity of N,N-dimethylolimidazolidone-2.

EXAMPLE 5 The procedure of Example 2 is followed but omitting the pyrrolidone-2. One-half of the mixture has 6% (with reference to the solids content) of epsilon-caprolactam added to it prior to condensation (Sample 2), while the other half is processed without additive (Sample 1). The samples obtained had the following water contents and,

after storage for six weeks at 40 C., the following contents of water-insoluble constituents:

Sample 1 2 Percent Water 0.64. 0.83 Insoluble. 0. 93 0. 37

EXAMPLE 6 An aqueous solution of urea and formaldehyde (molar ratio 1:1.75, solids content 46%) is adjusted to a pH value of 7.6 with triethanolamine, kept for sixty minutes at 35 C. and then stirred for three days at 22 to 25 C. The aqueous suspension of crystals is divided into four parts. Sample 1 is spray-dried, without adadditive, at a dryer inlet temperature of 150 C. and a dryer outlet temperature of 70 C.; Sample 2 is spray-dried under the same conditions after an addition of 6% of hexahydropyrirnidone-Z (with reference to the solids content in the aqueous suspension); Sample 3 is spray-dried after an addition of 3% of 4,5-dihydroxyimidazolidone-2; and Sample 4 is spray dried after an addition of 4% of N- hydroxymethylpyrrolidone.

The powders obtained by the spray drying are all soluble in water (140 g./l.) without residue. They have the following properties:

Sample Water content, percent 1 pH of aqueous solution 8 After having been stored for four weeks at 40 C., the spray-dried products contain the following amounts of water-insoluble constituents:

EXAMPLE 7 1000 parts of a methylolurea spray-dried product prepared by spray drying a 45% aqueous methylolurea paste (which has been prepared by reaction of urea and formaldehyde for two hours in the molar ratio 1:1.75 at 35 C., stirring at room temperature for fifty hours and adjustment to pH 7.5 with triethanolamine (is well mixed with 30 parts of finely powdered imidazolidone-Z. Both the starting product and the mixture are soluble in water without residue. After storage for four weeks at 40 C., the starting product contains 0.6% of water-insoluble constituents while the mixture contains only 0.3%.

We claim:

1. A spray-dried agent for textile finishing having improved stability in storage which consists essentially of:

(a) at least one methylol urea obtained by reacting urea and formaldehyde in the molar ratio of 111.4 to 1:22 as the active component;

(b) 2 to 8% by weight with reference to component (a) of at least one substance having the formula:

z-o .0 ir-r'c (I) in which Z denotes a radical selected from the group consisting of NH and -N(CH OH)--, X denotes a radical selected from the group consisting of NH, N(CH OH), CH and -O- and Y denotes a divalent radical selected from the group consisting of alkylene of 2 to 4' carbon atoms and said alkylene substituted by at least one of the radicals: hydroxyl, alkyl having one to four carbon atoms and alkoxyl having one to four carbon atoms, as stabilizer, and

(c) up to 2% by weight of water.

2. An agent as claimed in claim 1 which contains 3 to 6% by weight of component (b) with reference to component (a).

3. An agent as claimed in claim 1 which contains imidazolidone-Z as component (b).

4. An agent as claimed in claim 1 which contains dimethylolimidazolidone-Z as component (b).

5. An agent as claimed in claim 1 wherein said molar ratio is 1:14 to 121.85.

6. A process for the production of a textile-finishing agent which comprises:

(1) reacting urea and formaldehyde together in a molar ratio of 111.4 to 1:1.85 in aqueous solution at a pH value of 6.5 to 8.5 and at a temperature of 30 to 40 C. for up to five hours to form at least one methylol urea;

(2) cooling the reaction mixture to 15 to 28 C.;

(3) stirring the reaction mixture at 15 to 28 C. for

at least twenty-four hours;

(4) spray-drying the resultant crystal slurry; and

(5) adding to the reaction mixture during one of the stages (1) and (3) from 2 to 8% by Weight, with reference to said methylol urea, of at least one substance of the formula l -x (I) in which Z denotes a radical selected from the group consisting of NH and N(CH OH), X denotes a radical selected from the group consisting of NH-, -N(CH OH), CH and O' and Y denotes a divalent radical selected from the group consisting of alkylene of 2 to 4 carbon atoms and said alkylene substituted by at least one of the radicals: hydroxyl, alkyl having one to four carbon atoms and alkoxyl having one to four carbon atoms.

7. A process as claimed in claim 6 wherein spray drying is carried out at a dryer inlet temperatre of from to C. and a dryer outlet temperature of from 50 to 80 C.

8. A process as claimed in claim 6 wherein the urea, formaldehyde and water are used in such amounts that the crystal slurry formed in stage (3) has a dry residue of from 40 to 50% by weight.

References Cited UNITED STATES PATENTS 2,755,198 7/1956 Stewart 260--309.7 2,901,463 8/1959 Hurwitz 8-116.3 3,079,279 2/ 1963 Vanloo 260 3 09.7

HERBERT B. GUYNN, Primary Examiner US. Cl. X.R. 

